Many VoIP phones today support the Session Initiation Protocol (SIP), which is a standard used in setting up and tearing down voice or video calls transmitted over packet-based networks. SIP is a peer-to-peer protocol in which all voice/video communications between the caller and callee are performed using the Real-time Transport Protocol (RTP). Resetting or restarting of VoIP phones is typically achieved by the call management agent (e.g., CallManager) sending unsolicited call control messages to the client phone to trigger the reset/restart. These messages cause the phone to reboot, re-read its configuration files and re-register with the CallManager. (The term “reset” commonly refers to a long power-on cycle, whereas “restart” normally refers to quicker re-initialization of the configuration and protocol stack. The term “warm restart” denotes a sequence of re-initialization operations that is performed to reset a previously running system or device.)
One problem that exists is that legacy low-end and mid-range SIP phones can be reset, but they implement different mechanisms that are incompatible with recently developed call management architectures. Still another problem with prior art approaches is that they are vulnerable to malicious attacks wherein an unscrupulous hacker can indiscriminately send out reset/restart messages to a huge number of IP phones.